US3364383A - Waveguide impedance transformers - Google Patents

Waveguide impedance transformers Download PDF

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Publication number
US3364383A
US3364383A US303054A US30305463A US3364383A US 3364383 A US3364383 A US 3364383A US 303054 A US303054 A US 303054A US 30305463 A US30305463 A US 30305463A US 3364383 A US3364383 A US 3364383A
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United States
Prior art keywords
waveguide
quarter
transformer
guide
impedance
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Expired - Lifetime
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US303054A
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English (en)
Inventor
Cooper Brian Frederick
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Teledyne UK Ltd
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English Electric Valve Co Ltd
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Publication date
Priority claimed from GB3963162A external-priority patent/GB992048A/en
Application filed by English Electric Valve Co Ltd filed Critical English Electric Valve Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J23/00—Details of transit-time tubes of the types covered by group H01J25/00
    • H01J23/36—Coupling devices having distributed capacitance and inductance, structurally associated with the tube, for introducing or removing wave energy

Definitions

  • This invention relates to waveguide impedance transformers such as are often used, in microwave technique, for such purposes as coupling the output resonator of a microwave oscillator, such for example as a magnetron, to its output waveguide. More specifically the invention relates to waveguide impedance transformers of the quarter-Wave type.
  • FIGURE 1 is a diagrammatic representation of the prior art quarter-wave type of impedance transformers to which this invention relates;
  • FIGURE 2 is an outer end view of a rectangular waveguide having a circular flange within which is mounted one illustrative waveguide impedance transformer of this invention
  • FIGURE 3 is an elevation view of the waveguide and waveguide impedance transformer of FIGURE 2 partially in section;
  • FIGURE 4 is an inner end view of the waveguide and waveguide impedance transformer of FIGURE 2;
  • FIGURE 5 is an elevation view of a slotted block employed in the waveguide impedance transformer of this invention.
  • FIGURE 6 is an end view of the slotted block of FIGURE 5;
  • FIGURE 7 is a plan view of the slotted block of FIGURES 5 and 7;
  • FIGURE 8 is a perspective view partially in section showing the embodiment of FIGURES 2, 3, and 4 attached to the output of a microwave oscillator;
  • FIGURE 9 is an equivalent diagrammatic representation of the embodiment of FIGURES 2, 3, and 4.
  • the output resonator of a microwave oscillator is represented by the block 1, the output of the resonator being indicated by dots.
  • a load (not shown) is fed through a main waveguide 2 via an intermediate quarter-wave length of waveguide-commonly termed a transformer waveguide 3.
  • the external Q value of the resonator 1 is determined by the impedance Z presented by the load at the resonator output. If Z is the characteristic impedance of the transformer waveguide 3, which is one quarter of a wavelength long, and if the main waveguide 2 is matched and is of characteristic impedance Z the value of Z at the resonator output is given by:
  • the external Q value of the resonator depends on the value of Z it is important, for eflicient and satisfactory operating, to pre-determine this value accurately. It. is also desirable to allow adjustment in coupling to compensate for other dimensional variations.
  • the waveguide 3 is accurately machined to determine its dimensions with precision. This is difficult and expensive to do, having regard to the high degree of accuracy commonly required.
  • the present invention seeks to provide improved waveguide impedance transformers of the quarter-wave type without this disadvantage and which shall be such that the transformer waveguide which forms part of the transformer can be i United States Patent 0 easily adjusted, after manufacture. In this way cost of manufacture is materially reduced.
  • a quarter-wave type waveguide impedance transformer includes .a transformer waveguide which is deformable to permit alteration of the characteristic impedance thereof to adjust the same accurately to a desired pre-determined value.
  • FIGS. 2 to 8 inclusive these shown an embodiment of this invention wherein the main waveguide 2 of characteristic impedance Z is a rectangular waveguide one broad wall of which appears in FIG. 3 in which the guide is shown broken away.
  • the said main guide terminates in a rectangularly apertured circular flange member 4 which is adapted to be fitted to the output resonator of a magnetron or other microwave device.
  • a glass or other suitable vacuum-tight window (not shown) may be sealed across the cross-section of the guide 2 near the flange member 4 in accordance with customary practice.
  • each block 5 is the same as the larger dimension of the interior cross-section of the guide 2; a second dimension y of each block is equal to one quarter of the intended working wave length; and the third imension z is of such value that 2z is less than the smaller dimension of the interior cross-section of the guide 2.
  • Each block 5 has a slot 6 of length less than one quarter of a guided wave length cut in it parallel to and close to one of the two faces which are of dimensions x by y, the slot running the full length of the dimension x.
  • the blocks 5 are fixed in the mouth of the guide 2 with their slotted faces facing into the guide 2 and the slots 6 near the space which is left between the blocks.
  • the arrangement is best shown in FIGS. 4 and 8.
  • the quarter-wave transformer waveguide 3 is constituted by the space between the blocks 5 and it will be seen that, in the construction shown, the cross-section of the guide hasone dimension x and the other dimension, which will hereinafter be termed the height dimension, equal to the separation between the adjacent faces of the blocks 5.
  • This dimension can be readily adjusted over a range which is adequate for practical purposes, by inserting a suitable tool into the waveguide 2 (before, of course, the window-if anyis fitted therein) and widening the slots by inserting the tool therein or, if desired, narrowing the slots by inserting the tool between the blocks 5.
  • the adjustment is made such that the height of the transformer guide 3 is constant (at any cross section) over the dimension x.
  • the slots 6 shall extend for the full length x as is the case in the illustrated embodiment. This is, however, not essential and the slots can be shorter giving adjustment over a shorter length and non-constant height for the transformer waveguide 3 over a given cross section.
  • the slots form two short-circuited waveguides which are not cut off at the transformer design frequency.
  • the design must, of course, be such that they are of acceptably small electrical effect on the performance of the transformer. This requirement, and how it may be satisfied, will be better understood from FIG. 9, which is an approximately equivalent diagrammatic representation of the illustrated embodiment.
  • this equivalent diagram comprises the resonator 1, the transformer waveguide 3, the main waveguide 2 and two branch guides 66 constituted by the slots 6. If the branch waveguide has a low attenuation constant and its characteristic impedance is Z then Z the impedance presented by the series branch waveguide at its mouth (see FIG. 9) is given by:
  • Z Z tan a 1 where on is the phase constant and 1 is the dimension shown in FIG. 9 (2) If a and 11 are, respectively, the broad and narrow cross sectional dimensions of the main guide 2 and a and 11 are respectively, the broad and narrow crosssectional dimensions of the branch guide 66.
  • a quarter-wave impedance transformer including a quarter-wave length of rectangularly sectioned guide having two opposite broad faces of thin metal formed of thicker metal portions incompletely slotted to a depth of substantially one-quarter of a wave length and defining said thin metal faces supported by bendable necks of metal carrying said thin metal faces.
  • a transformer according to claim 1 for use in association with a main waveguide in communication therewith, the width of the slotting of said tricker metal portions being substantially less than the width of the main waveguide.
  • a magnetron structure comprising in combination a magnetron and a quarter-wave impedance output transformer as defined in claim 1.
  • a magnetron structure comprising in combination a magnetron and a quarter-wave impedance output transformer as defined in claim 4.
  • a quarter-wave impedance transformer comprising a quarter-wave length of rectangularly cross-sectioned wave guide, a pair of metal portions having opposed broad face portions comprising opposed broad faces of said quarter wave length of wave guide, each of said metal portions having a slot therein in proximity to said face portions to define relatively thin Walls intermediate said broad faces and said slots, and neck portions interconnecting said thin walls and the remainder of said metal portions, said thin Walls being adjustable toward and away from each other for adjustment of the characteristic impedance of said quarter-wave impedance transformer.
  • each of said slots comprises a short circuited wave guide.

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  • Control Of Motors That Do Not Use Commutators (AREA)
US303054A 1962-10-19 1963-08-19 Waveguide impedance transformers Expired - Lifetime US3364383A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB3963162A GB992048A (en) 1962-10-19 1962-10-19 Improvements in or relating to waveguide impedance transformers
GB3963163 1963-06-28

Publications (1)

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US3364383A true US3364383A (en) 1968-01-16

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US303054A Expired - Lifetime US3364383A (en) 1962-10-19 1963-08-19 Waveguide impedance transformers

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US (1) US3364383A (en, 2012)
CH (1) CH413930A (en, 2012)
DE (1) DE1293266B (en, 2012)
NL (2) NL143737B (en, 2012)
SE (1) SE319220B (en, 2012)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4041420A (en) * 1976-06-30 1977-08-09 Riblet Henry J Shunted stepped waveguide transition
US4797597A (en) * 1986-12-22 1989-01-10 Bostrom Norman A Microwave ion source

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IT1123315B (it) * 1979-09-25 1986-04-30 Rockwell Rimoldi Spa Dispositivo caricatore delle pezze in rotolo per macchine faldatrici

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2411534A (en) * 1943-03-30 1946-11-26 Bell Telephone Labor Inc Impedance transformer
US2432093A (en) * 1942-07-30 1947-12-09 Bell Telephone Labor Inc Wave transmission network
US2466922A (en) * 1946-02-12 1949-04-12 Bell Telephone Labor Inc Electron discharge device
US2526399A (en) * 1943-12-23 1950-10-17 Westinghouse Electric Corp Output connection for ultra high frequency devices
US2531437A (en) * 1942-03-31 1950-11-28 Sperry Corp Wave guide impedance transformer
US2576186A (en) * 1946-10-22 1951-11-27 Rca Corp Ultrahigh-frequency coupling device
US2607849A (en) * 1943-10-02 1952-08-19 Edward M Purcell Control of polarization in wave guides and wave guide systems
US2666869A (en) * 1946-06-21 1954-01-19 Albert M Clogston Magnetron output coupling system
US2701343A (en) * 1947-08-28 1955-02-01 Bell Telephone Labor Inc High q resonant cavity
US2805337A (en) * 1955-03-16 1957-09-03 British Thomson Houston Co Ltd Magnetron oscillators and their associated output circuits

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2433368A (en) * 1942-03-31 1947-12-30 Sperry Gyroscope Co Inc Wave guide construction

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2531437A (en) * 1942-03-31 1950-11-28 Sperry Corp Wave guide impedance transformer
US2432093A (en) * 1942-07-30 1947-12-09 Bell Telephone Labor Inc Wave transmission network
US2411534A (en) * 1943-03-30 1946-11-26 Bell Telephone Labor Inc Impedance transformer
US2607849A (en) * 1943-10-02 1952-08-19 Edward M Purcell Control of polarization in wave guides and wave guide systems
US2526399A (en) * 1943-12-23 1950-10-17 Westinghouse Electric Corp Output connection for ultra high frequency devices
US2466922A (en) * 1946-02-12 1949-04-12 Bell Telephone Labor Inc Electron discharge device
US2666869A (en) * 1946-06-21 1954-01-19 Albert M Clogston Magnetron output coupling system
US2576186A (en) * 1946-10-22 1951-11-27 Rca Corp Ultrahigh-frequency coupling device
US2701343A (en) * 1947-08-28 1955-02-01 Bell Telephone Labor Inc High q resonant cavity
US2805337A (en) * 1955-03-16 1957-09-03 British Thomson Houston Co Ltd Magnetron oscillators and their associated output circuits

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4041420A (en) * 1976-06-30 1977-08-09 Riblet Henry J Shunted stepped waveguide transition
US4797597A (en) * 1986-12-22 1989-01-10 Bostrom Norman A Microwave ion source

Also Published As

Publication number Publication date
NL298752A (en, 2012)
SE319220B (en, 2012) 1970-01-12
DE1293266B (de) 1969-04-24
CH413930A (fr) 1966-05-31
NL143737B (nl) 1974-10-15

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